Nico Rosberg quickest as Kevin Magnussen's car ignites in FP1

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SEPANG, Malaysia -- Nico Rosberg beat Lewis Hamilton to the fastest time by 0.494s during first practice at the Malaysian Grand Prix in a session interrupted by a fire on Kevin Magnussen's Renault.

The Mercedes drivers were closely matched earlier in the session but on his sixth lap on a set of soft tyres, Rosberg extended his advantage by over 0.5s. Hamilton improved using the slower medium tyre, but did not hook up all his best sectors on one lap and ended up 0.494s shy of his teammate. However, a long run on the medium tyres looked particularly impressive, suggesting Hamilton has yet to show his true pace over one lap.

Kimi Raikkonen was third fastest in the Ferrari, a further 0.594s off Hamilton and just 0.016s ahead of teammate Sebastian Vettel. Last year's race winner complained of vibrations when he set his time on a set of soft tyres early in the session and later returned to the pits to rectify the issue, before completing another seven laps on the same set of tyres.

Fernando Alonso was fifth fastest as he debuted Honda's latest power unit upgrade in the back of the McLaren. He will revert to the old-spec engine for qualifying and the race, but will take some satisfaction from being just 0.179s off Vettel's Ferrari using the same tyre compound.

Daniel Ricciardo was sixth fastest but set his best time on used hard tyres after Red Bull opted not to complete a time on the softs. Max Verstappen was 0.220s off Ricciardo despite using the faster medium tyres, but it is unlikely Red Bull showed anything approaching its true pace during the session.

The Force Indias of Nico Hulkenberg and Sergio Perez were eighth and ninth fastest after they also steered clear of the soft tyres and focused entirely on longer runs using the mediums and hards. Jenson Button, whose McLaren is not equipped with the updated Honda, was tenth fastest after sticking exclusively to the mediums throughout the session.

Outside the top ten, only Felipe Nasr set his fastest time on the soft tyres, with the rest clocking their best effort on the mediums. Williams stayed true to its usual Friday form of being well off the pace, with Felipe Massa down in 18th.

The fire on Magnussen's car occurred as he returned to the pits after just his second lap. The airbox became engulfed in flames as mechanics started to push the car back into the garage, forcing Magnussen to leap from the cockpit as the rest of Renault's pit crew moved in to extinguish the fire. The car had to be drained of fuel before the fire could be brought under control, resulting in the session being suspended for 15 minutes under red flags.